Now showing items 1-10 of 15
Using crop genetic diversity to improve resilience: Agronomic potential of evolutionary breeding under differing management systems
Mainly within organic and low-input cropping systems, evolutionary breeding based on the creation of heterogeneous evolving composite cross populations (CCPs) has been gaining attention. The aim of this dissertation is to assess the agronomic potential and yield stability of wheat CCPs in comparison to pure line varieties under differing management systems. Three winter wheat CCPs were created in the UK in 2001, based on parental varieties that were selected for either their high yield or baking quality. The baking ...
Resistance Based Integrated Pest Management Strategy for Globodera rostochiensis and Globodera pallida in Potato Cropping Systems
Potato cyst nematodes (PCN), Globodera rostochiensis and G. pallida are important potato pests responsible for high yield losses globally. The ability of PCN to persist in the soil for a long time makes their management challenging and therefore these nematodes are under strict quarantine regulations in many countries. Nevertheless, both PCN species have recently been reported in potato cropping systems in Kenya. Resistant potato cultivars reduce nematode densities in the field below damage threshold levels and thus ...
Untersuchungen zur Bedeutung phytotoxischer Sirodesmine und zur induzierten Seneszenz in Interaktionen von Phoma lingam mit Brassica-Arten
Ziel dieser Arbeit war es, die Bedeutung phytotoxischer Sirodesmine in Interaktionen von Phoma lingam mit Brassica napus und Brassica juncea zu untersuchen. Ein weiteres Interesse galt dem Einfluß einer induzierten Seneszenz auf die Resistenzeigenschaften. Zur Isolierung von Sirodesmin PL wurde ein Säulenchromatographieverfahren auf Kieselgelbasis entwickelt. Mit dieser Methode konnten bis zu 100 µg Sirodesmin PL in reiner Form pro Arbeitsgang chromatographiert werden. Sirodesmin PL wurde in verschiedenen Dosierungen ...
Genetic variation of and environmental effects on inducibility of resistance in tomatoes (Solanum lycopersicum L.) to Phytophthora infestans (Mont) de Bary
Many plant strengtheners are promoted for their supposed effects on nutrient uptake and/or resistance induction (IR). In addition, many organic fertilizers are supposed to enhance plant health and several studies have shown that tomatoes grown organically are more resistant to late blight, caused by Phytophthora infestans to tomatoes grown conventionally. Much is known about the mechanisms underlying IR. In contrast, there is no systematic knowledge about genetic variation for IR. Therefore, the following questions ...
Development and Integration of Biocontrol Products in Branched Broomrape (Phelipanche ramosa) management in Tomato
Parasitic weeds of the genera Striga, Orobanche, and Phelipanche pose a severe problem for agriculture because they are difficult to control and are highly destructive to several crops. The present work was carried out during the period October, 2009 to February, 2012 to evaluate the potential of arbuscular mycorrhizal fungi (AMF) to suppress P. ramosa on tomatoes and to investigate the effects of air-dried powder and aqueous extracts from Euphorbia hirta on germination and haustorium initiation in Phelipanche ramosa. ...
The Suppressive Nature of Compost against Pythium spp: evaluation of compost-based applications in two host pathogen systems using bioassays and molecular fingerprinting
The suppressive effect of composts on soil-borne plant pathogens has been widely reported in the scientific literature. However, the role of the compost microbiome, in this respect, is still not well understood. The general goal of this research was the molecular-biological characterisation of the microbiomes of two compost types within the host-pathogen system Pythium ultimum and cucumber, thereby contributing to understanding the role of the microbial structure of the chosen composts in this specific system. An ...
Pathogens occuring in the winter pea-maize-winter wheat rotation, their host specificity and the potential of compost in suppressing foot and root disease of peas
The overall aim of the work presented was to evaluate soil health management with a specific focus on soil borne diseases of peas. For that purpose field experiments were carried out from 2009 until 2013 to assess crop performance and pathogen occurrence in the rotation winter pea-maize-winter wheat and if the application of composts can improve system performance. The winter peas were left untreated or inoculated with Phoma medicaginis, in the presence or absence of yard waste compost at rate of 5 t dry matter ha-1. ...
Etiology of Maize Root rot in Oman: Causal agents and effects of a compost based organic growing system
Summary: In Oman, the main cereal crop Maize is facing serious problems due to high salinity, alkaline soils with low organic matter, high temperatures, and root rot diseases. Production peaked at 40,000 t in 2011 but dropped to less than 15,000 t in 2014. A survey on maize root rot in eight maize growing governorates in Oman yielded nine fungal and oomycetes species of which Pythium arrhenomanes and Fusarium fujikuroi were first reports on maize in Oman. Both are able to attack multiple hosts. Under controlled ...
Studies on the diversity of the main necrotrophic pathogens on wheat and barley Pyrenophora tritici-repentis and Cochliobolus sativus
Leaf blights such as tan spot of wheat (Pyrenophora tritici-repentis) and spot blotch of barley (Cochliobolus sativus) are among the main constraints in achieving high and stable yields and are the main concerns among the several intrinsic drawbacks of narrow cropping sequencesas both are residue borne. The development of useful and durable resistance against prevalent races requires detailed information on the virulence diversity of the pathogen and the type of resistances available in the host. Thus, the focus of ...
Agrobiodiversity through evolutionary plant breeding – System specific adaptation of agronomic and morphological traits and effective populations size in composite cross populations of winter wheat
Der Schwerpunkt der vorliegenden Arbeit ist die Beschäftigung mit Züchtungsmethoden, die eine Erhöhung der Agrobiodiversität mit sich bringen, außerdem werden die Auswirkungen diversifizierter Anbausysteme betrachtet.